Electrolytic facsimile recording



Patented Dec. 29, 19 42 Myer Solomon, Westmont, N. J.,

assignor to Radio Corporation of America, a corporation ofDelaware No Drawing- Application December- 8, 1937,

Serial No. 118,742

24 Claims.

This invention relates to the electrolytic formation of azo and other dyes; particularly in connection with facsimile recording.

Various different types of' facsimile receivers are used at the present time, and in all of them pictures, printed matter, or other characters are produced on a sheet of paper in response to variations in electrical currents which are received from the transmitter station. In one type thereproduction of the character or indicia is fer of the carbon to the'record paper is accomplished by means of an electromagnetically controlled printer bar. In such a device the recording paper and carbon paper are placed in the facsimile receiver and are moved forward at relatively slow rates while line increments of the material being received are reproduced through the application of varying degrees of pressure to the printer bar, in order that varying amounts of the carbon will be transferred from the carbon paper to the recording paper. Such a device for facsimile recording is shown in the Patent to Charles J. Young, Reissue No. 20,152, October 2'7,

In another type, a light sensitive recording paper is used and the amount of light permitted to strike the paper is controlled in accordance with the electrical variations transmitted by the facsimile transmitting device. In this type some developing or fixing process generally follows.

In still another type a stream of hot air is directed against a .heat responsive recording paper, the intensity of'the heat or the amount of hot air being controlled in response to the energy transmitted by the facsimile transmitting device. Another type uses a jet of ink or some colored fluid, the jet being permitted to strike, or prethrough the use of carbon paper and the transvented from striking, the recording paper according to the series of signals received from the transmitting device. The patent to Richard H. Ranger, No. 1,770,493 of July 15, 1930, shows for example, devices wherein jets of hot air or ink are used for facsimile recording.

In the facsimile receiving or recording systems referred to above, the production of half tones and shades such as occur in the reproduction of pictures, is somewhat difficult, since, for instance, in the carbon paper method, the transfer of the carbon to the recording paper is somewhat critical in response to the pressure applied to the printer bar. Furthermore, the use of hot air or ink jets is not entirely satisfactory since such systems are difficult to control and to maintain in proper operation.

iii

. In the present invention, it is proposed to produce the picture or printed matter on the recording paper in the'form Of a, dye, the amount of such dye deposited being a function of the amount of current caused to flow through the recording paper. When the image is so formed, the pressure of the printer bar is. maintained-constant and the amount of current which is passed through increments of the paper is varied in accordance with the light and darkportions present on the picture or printed matter being scanned at the facsimile transmitter. when dyes are so formed by electrolytic action, varying half tone shades may be produced by merely regulating the amount of the current which is caused to flow through the recording paper.

In the present invention, facsimile recording is accomplished by any of the following three general methods of electrolytic dye formation, viz., (I) electrolytic coupling, or causing azo dye formation by preparing a diazonium salt solution and subjecting the solution and a coupling compound to an electric current; (11) electrolytic diazotization, or forming a diazonium compound by subjecting asolutioncontaining amine,

nitrite, and a coupling compound to an electric current and permitting the formation of an azo dye by spontaneous coupling with the coupling compound; and (III) electrolytic oxidation, or forming dyes by electrolytically oxidizing chemicals that react to produce dyes .when oxidized.

The principle of operation of the present invention as applied to (I) electrolytic coupling resides broadly in the fact that a diazonium and a coupling compound which are neutral or mildly acid in reaction will combine to form a dye when subjected to an electric current, the dye being produced at the alkaline or negative electrode.

The principle of operation of the present invention as applied to (II) electrolytic diazotization resides broadly in the fact that when an electric 'current flows through a mildly alkaline mixture containing a primary aromatic amine l and a metallic nitrite, a diazonium compound is formed at the acid or positive electrode, and an azo dye subsequently forms within a few seconds if a coupling compound is also present.

The principle of operation of the present invention as applied to (III) electrolytic oxidation resides broadly in the fact that certain compounds or solutions produce dyes when oxidized. When any neutral, mildly acid, or mildly alkaline electrolyte is subjected to an electric current, acidification and oxidation are brought about at the positive electrode whilethe electrolyte is alkalized and reduced at the negative electrode.

in some instances oxidation alone causes a formation of the dye whereas in other instances both oxidation and acidification are necessary.

It'is therefore one purpose of the present invention to provide means for forming diazonium compounds by the action of an electric current on mixtures or solutions containing primary aro- "matic amines and metallic nitrites.

compound to an electric current. I

I applied.

compounds.

It is a still further purpose of the present invention to provide means for forming diazonium compounds by the action of an electric current on mixtures orsolutions containingprimary aromatic amines and metallic nitrites, for the production of azo dyesfrom these diazo compounds by spontaneous coupling with coupling compounds, and-the provision of means whereby these dyes and their formation in situ may be applied to facsimile recording.

It is a still further purpose of the present invention to provide means to produce varying degrees of color on any fabric, paper, cloth or other material which has been treated with amines. nitrites and coupling compounds by causing varying amounts of an electric current to be passed therethrough.

Still another purpose of the present invention resides in the formation of azo dyes in situ by subjecting a diazonium compound and a coupling A further purpose of the present invention resides in the formation of dyes by electrolytic oxidation of certain compounds.

Another purpose of the present invention resides in the formation of dyes by passing an elec tric current through a solution whereby the solution may be acidified and/or oxidized at the positive electrode to produce a dye.

A still further purpose of the present invention resides in the application of any of the above mentioned methods of and means for producing dyes to facsimile recording, to the production of colors in any material which may be treated with a solution, and to the formation of dye pigments.

A still further purpose of the present invention resides in the addition of auxiliary chemicals, principally reducing agents, to the chemicals with which materials are treated so that azo dyes may be formed thereon electrolytically. in order to prevent or retard. the gradual darkening of the background of such treated materials.

A still further purpose of the present invention resides in the addition of auxiliary chemicals, such as metallic salts, complex cyanides, etc., to the chemicals wtih which materials are to be treated for electrolytic dye formation, in order to act as dye mordants or otherwise to improve the fastness to light or washing or to modify the color.

Other purposes and advantages of the present invention will become apparent to those skilled in the art from the following more specific description of the present invention.

The theory of the use of electrolytic coupling of diazonium compounds (I) is based primarily on the fact that diazonium compounds under certain conditions may be mixed with coupling compounds without coupling or dye formation actually taking place until the mixture is subjected to an electric current. Sometimes coupling inhibitors may be present to prevent undesired spontaneous coupling where the current is,not

For facsimile recording, the recording paper is made wet by amildly acidsolution containing diazonium and couplingv compounds, and is then Gil passed through the facsimile receiving or recording apparatus in such a manner that electriccurrent causes dye formation on spots corresponding to dark spots on the transmitted picture or printed matter, in accordance with the electrical impulses being received from the facsimile transmitting device.

A water solution is prepared containing essentially the following chemicals:

I. A neutral electrolyte, such as sodium or potassium chloride or sulphate. This serves to permit the flow of electric current through the paper.

II. A diazonium salt, preferably one sensitive to light.

III. A coupling compound, preferably phenolic in nature, coupling only under alkaline conditions.

IV. A small amount of an acid, to maintain the acidity of the solution and thus prevent premature coupling.

In addition to the four essential ingredients, the solution may or may not contain small amounts of the following: (1) coupling inhibitors, as semicarbazide or hydrox'ylamine, which aids acidity in preventing premature coupling, (2) reducing agents, as sulphites, hydrosulphites, thiosulphates, hydroquinone, glucose, tartrates, oxalates, stannous chloride, etc., which prevent the gradual darkening of the background or (3) salts of copper, iron, chromium, aluminum or other metals, which act as mordants or otherwise aifect the color of the dyes or the light sensitivity of the diazonium salt.

The azo dye is formed at the negative or alkaline electrode, the electric current creating an alkaline condition which persists long enough for the diazonium and the coupling compounds to combine with each other. The following chemical equation represents the reactions that are caused by the current flow, Ar and Ar representing benzene or naphthalene rings with or without one or more substituent groups:

A|-Nz+ HAr'OH ArNq NAr'OH+ H (diazonium (coupling (A10 dye) (nascent salt) compound) hydrogen) The nascent hydrogen may either combine with itself and pass oil. as molecules of hydrogen gas (H2), or react with some of the'chemicals in the solution.

The synchronization of paper feed and current flow. with the facsimile signals causes dye to be formed only at points corresponding to' gray, colored or black points on the original subject matter transmitted,.thus producing a facsimile recording. Half-tones are obtained because the intensity of color is a function of the amount of dye formed, which increases with increase of current strength. After recording has been accomplished, the paper is exposed to strong light in'order to destroy the unchanged diazonium salt, and thus fix the white background. The

' recordings may also be washed, thereby removingthe unused chemicals, as most of these dyes which may be used to form a solution whereby a dye may be produced by electrolytic coupling:

follows: I

Ingredients Gram-molecular weight used Amount?! (1) Amine-source oi .033 Varies with molecdiaaonium salt. ular weight of amine.

(II) Hydrochloric acid: .08 80cc.

normal solution (or equivalent amount of other acids).

(III Sodium nitrite.. .03 2.07 grams.

(1 Coupling com- 010to0.l5 Varies with molecpound: hydroxy ular weight or aromatic comcompound. pound.

(V) Sodium chloride... 1.0........... 58.47 grams.

(VI; Ice and water to otal volume 011001 cc.

(VII Sodium hydroxide: .05 to .1 50 to 100 cc. Used normal solution only in special NaOH. cases.

(VIII) Ailliary chemi- Varying amounts. i

' The procedure of mixing the ingredients is as The diazonium salt, I, is dissolved inn, with boiling and/or addition of small amounts of water if necessary. The resultant amine hydrochloride solution is then cooled below 8 degrees centigrade, preferably by adding ice. The sodium nitrite, III, is dissolved in 25 to 50 cc. of water and poured slowly (about one minute) into the cooled solution with constant agitation. Generally one or more color changes take place accompanied by a slight effervescenca due to nitrogen gas formation. It is desirable to keep this gas formation to a minimum, which is accomplished by keeping the mixture cool. In some cases very little gas forms even at room temperature. The coupling compound IV and the sodium chloride V are dissolved either together or separately in water and added to the mixture of I, II and III after this has stood for at least fifteen minutes. The sodium hydroxide VII is used only if I is an amino sulphonic or carboxylic acid insoluble in II. Auxiliary chemicals are usually added "with the coupling compound IV. Stable diazonium salts, such as nitrosamines, chlorostannates or other double salts, etc., may be used instead of amines and sodium nitrite, in which case the ingredients are merely dissolved in water to a total of one liter.

In an amine hydrochloride, or a poly-amino compound is used as ingredient (I), the amount of hydrochloric or other acid is changed accordacid for the .03 of sodium nitrite, in addition to the acid requiredto neutralize all of the amino groups present in the amino compound.

The amount ofcoupling compound varies with its, coupling strength. Usually darker colors are produced by using more than one gram-molecular equivalent of diazonium salt per gram-molecular equivalent of coupling compound, due prob.- ably to partial formation of dyes having two or three molecules of diazonium salt coupled to one molecule of the coupling compound.

Ordinary table salt may be used to supply the sodium chloride (ingredient V) or other strong neutral electrolytes may be substituted. It need not be accurately weighed, as any amount be- I tween 40 and 120 grams per liter gives practically identical recordings.

The amounts of the ingredients may be widely varied from those given above, provided that no uncombined nitrite remains in solution when the coupling compounds are added. This may be accomplished most easily by using a 10% excess of amine or by adding a small amountof urea to the amine-nitrite mixture before adding the remaining ingredients.

The preparation may be simplified somewhat by using solid ingredients exclusively and premixing the dry powders, so that the ultimate user will merely dissolve each of three powders separately in water, mix the resulting solutions in the proper order, and finally add more water to the required volume. Solid acids, such as tartaric, citric, oxalic, formic, sodium or potassium acid sulphates, etc., are used for ingredient II instead 35 of hydrochloric acid. Powder A contains I, B

contains III, and C contains IV (and VIII if used). Ingredient II may be in either A or B, V may be in either A, B or C, and VII, when used, is placed in A (in which case II is in B).

Some of the solutions have been kept a week without losing their strength. They should be stored in the dark. Separate solutions of diazonium salts and coupling compounds are still more stable, and some of these may be kept for months.

A specific example, which is representative of the numerous solutions that have actually been used for electrolytic coupling, follows:

ingly, so that when I, II and m are finally w mixed there are .05 gram equivalent weights of g n 8 G m. No. Name Formula Use \fs ed per liter I p-Amino diethylanilinahy- NH,

drochloride. 4.4

v H N(CzHs).HCl Amines source oi diazo- II p-Amino d1methylanilino NR1 nium compounds.

hydrochloride.

. N(CH;).HC1

III Tartaric acid (CHOH C00H)1.H:O Acid. Source of hydrogen 6.22

' ion reducing agent to whiten background. IV Sodium nitrite NaNOz To diazotizeIand II 2.07

V Phloroglucinol 7 H0 0H Coupling Compound. .042

H VI Chicago or 28 acid SOzH Coupling compound 2. 39

OiH

H0 NH: VII Common salt NaCl Electrolyte 58.47 VIII Water To total volume oioneliter.

posure for one-half minute to a carbon are light,

or three to live minutes to direct sunlight bleaches the background until it is almost white. On standing for several weeks, the white background thus obtained becomes pale grey-brown. Washing the recordings with water removes very little of the color. and greatly reduces the background darkening.

Eramples of amines used for diazonium salts Color roduced with Amine phfiaroglucinol Para henylene dlamine Orange-brown on white. 4 am uodiphenylamine mono- Deep purple on white. hydrochloride. 1 m

4-amino dimethylanillne ye 2,5f-fiiaminoanisole dihydrochlo- Dark brown on pale tan.

Examples coupling compounds Compound Remarks Phloroglucinol Best coupling compoundtodate. Resorcinol Good, but give lighter colors Orcinoi colors than hloroglucinol. Pyrogallol Darker color, ut poorer definition and background than phloroglucinol. l-amino-8-naphthol 2,4 disul- Colors are more blue than phonic acid (Chicago or 28 phlo lucmol, I and backacid). groun gradually turns pale pink.

The'theory of the use of electrolytic diazotization (II) is based primarily on the fact that mixtures of primary aromatic amines and sodium nitrite (or other metallic nitrites) are stable in mild alkaline solution, the amino group being un-ionized and the nitrite ion having a negative electric charge. It is well known that diazotization of these compounds may be brought about by the addition of hydrogen ions, which is commonly accomplished by adding acid. In the present invention, the addition of the hydrogen ions is brought about by the action of positive electric current, thus causing immediate diazotization or diazonium-ion formation.

If coupling compounds are present in the reacting mixture, or are added after diazotization occurs, 'azo dyes are formed under the proper reacting conditions. When mixtures containing amines, nitrites and coupling compounds are diazotized electrolytically, coupling usually occurs spontaneously within less than a minute after the passage of the current, during and after the time that the electrically treated mixture is reverting to its original mild alkaline condition.

(when the current flows, the mixture becomes acid near the positive, and more alkaline near the negative electrode. 'When the current ceases, ionic mlgratio'n'soon causes a restoration of the originahmild alkalinity). In general, coupling compounds that react in alkaline solution give best results, because acid-coupling compounds must be sufliciently reactive for coupling to be completed before the original alkalinity is restored.

The following chemical equations express the reactions involved in electrolytic diazotization and subsequent coupling, Ar and Ar representing aromatic rings (benzene, naphthalene, etc.) with or without attached substituent groups, and X representing hydroxyl, primary, secondary or tertiary amino, active methylene groups, or any other groups that render a molecule capable of coupling.

(1) Electrolysis of water (2) Ionization .of primary amino groups ArNrn+He- Arm1,e

- (3) Nitrous acid formation.

The nascent oxygen and hydrogen formed, respectively, at the and electrodes, may either combine with some of the chemicals in the mix- V ture, or may pass ofl as molecules of oxygen or hydrogen gas. Since Reactions 4, 5 and 8 are irreversible, the products of these reactions do not revert to their starting points upon reversing the acidity or alkalinity, but either react further (4) (5) or remain as stable dye molecules (8).

In the application of the present invention to facsimile recording by electrolytic diazotization, the recording paper, film, or other material, is treated with a mixture containing a strong neutral electrolyte, a primary aromatic amine, so-

dium or other metallic nitrite, and a coupling compound, with or without other auxiliary chemicals. Damp or moist paper thus treated is subjected to electric current controlled by a facsimile scanner. Where positive electricity enters the treated paper, diazonium ions are formed,

which soon spontaneously unite with the coupling compound to form azo dyes only at points corresponding to similar areas on the subject being scanned. By varying the amines and coupling compounds, a great variety of recorded colors may be obtained. The three examples which follow may be regarded as representative of the numerous combinations that have been and may possibly be used.

9,806371 Exam: 2 Ingredients No. Name Chemical formula Use ill? omutlm n cmmuam. H dieuiemu om Amine c. m phonic acid. 7 NH:

(l1) Ohrcmctroplenlt Ooupllngcomponhd 8mm (III) Sodium hydroxide (normal To dissol I d m solution). the soluti oif m c. a 6200' (IV) Sodium nitrite (twice nor- To diazotize (I) cc.

mel solution). (V) Sodium chloride (common Electrolyte to permit curllzcgrems.

salt). rent to flow. (VI) Water Hi To total volume of 10004.

In the preparation of the solution, (I), (II); (III) and (V) are dissolved in about 800 cc. water. Since the commercial product (I) contains ammonia and some insoluble matter, the solution is filtered, and (IV) andthe remaining water are then added. Paper (preferably, 8.1-

though not necessarily, 100% rag stock, basis wt. 12 lbs., 17 x 22/500) feeds continuously from a roll, is immersed into and then removed from the solution, and while still wet or moist is passed between printing electrodes of a recorder. Positive electricity on one electrode forms pale purple recordings, which soon turn deep purplish blue on a white background. The background remains permanently white if the recordings are kept in a folder or file, but turns slightly lavender after several hours exposure to daylight. Washing the freshly recorded sheets thoroughly with water weakens the color only slightly, and greatly improves the permanence of the background. The formula of the dis-azo dye formed follows:

OH OH OH CH: BOrH 0H Hols on; H on H005 Exam 3 Ingredients "The solution is prepared similarly to Example 2, except that it is clear and does not require filtration. The same recording procedure gives orange-brown recordings on a white background, which turn pale yellow on exposure to light, and behave like Example 2 recordings when washed. The dye is a mono azo dye, as follows:

1 N21 noQon OiH H Name Chemical formula Amount used per liter of solution Sodium naphthlonate sNa (II) Phloroglucinol HO OH NaOH- Nelson;

NaOLL.

Sodium hydroxide (normal solution).

Sodium nitrite (twice normel solution).

Sodium chloride Coupling compound Tt i gake the solution alka- Seme es Example 2 Water Hi0 To total volume at 1000 00.

58.5 grams.

I'ixnnu 4 Ingredients Amount No. Name Chemiml formula U ls? solution (I) l-acetylnmino-l-I-Cleve: NH: Amine 9.228

acid. grams.

NHCOOHI (II) Gamma acid H Coupling compound and 2.390

amine. grams.

HOaS

(III) Sodium hydroxide (normal NaOH To dissolve (I) and (II) and 70 00.

solution) make the solution alkaline. (IV) Sodium nitrite (twice nor- NaNO, sameasExamplez e0.

mal solution). (V) Sosgilgn chloride (common NaCl do 52.6 grams. W Water: 11,0 To total volume of 1,000 cc.

The solution is prepared as in Examples 2 and 3 and filtration is unnecessary. Excellent dark purplish-brown recordings in a white background are obtained. On standing, even in the dark, the background gradually becomes pale purple, but if the freshly made recording is washed with water the background darkens much more slowly and to a far lesser extent than that of unwashed re- 85 cordings. The dye is a mixture, but consists In each instance, the recording paper is passed, through the facsimile receiver and after the azo dye has been formed thereon, in accordance with the subject matter scanned at the transmitter, the paper may then be subjected to a fixing bath It has been found that most solutions may be kept in storage for a considerable time and will still give good recordings even after two months or more, but best results are obtained when the -solutions are made fresh and are not kept in storage too long.

So far as the amines required for diazotization are concerned, any primary aromatic amine that is soluble in a mildly alkaline salt solution may for the purpose of making the azo dye more permanent in nature and/or to aid in the preservation of the white background. After fixation the paper may then be washed in order to remove any chemicals which remain in the undiazotized portions of the paper, in order materially or completely to reduce the effect of gradual fading of the color or darkening of the background when the recorded copy is later subjected to light and/or air.

In the preparation of the solutions the sodium nitrite must be added after at least part of the sodium hydroxide, to prevent the formation of diazonium salt in the solution. The preparation may be simplified still further by mixing the amine, coupling compound, and salt in the proper proportions before dissolving, together with a suflicient amount of sodium carbonate or other alkaline compound to make the solution alkaline when dissolved. A spoonful or other measured quantity of this mixture is dissolved in the required amount of water, and a measured amount of sodium nitrite solution (or a preweighed or measured amount of sodium nitrite powder) is added, when the solution is ready for use.

phonic groups increases the stability of the background toward light, but renders the dyes less fast to washing. I

The coupling compounds must be soluble in a mildly alkaline salt solution, and are subject to the same oxidation limitations as amines. Aromatic compounds with hydroxy, amino, or active methylene groups ortho or para to unsubstituted positions in the ring will usually couple. Sulphonic groups have the same effect as in amines. Resorcinol, phloroglucinol, the naphthols and their sulphonic acids, 8-hydroxy quinoline, and some amino naphthol sulphonic acids have given good results. Some amino naphthol sulphonic acids (for example, gamma, H, J S and 2S acids) may either diazotize or couple. Good recordings may thus be obtained, using the same chemical for both diazotization and coupling. However, most amino naphthol sulphonic acids give recordings that require washing in order to prevent the backgrounds from darkening during storage.

but such substitution the fastness of the the shade, or even change the color, of the dye.

' electrolytic diazotization.

harm. In addition to the sodium hydroxide required .to neutralize all strongly acidic groups in the amines and coupling compounds, 'a slightexcess (usually 20 cc. of normal NaOH solution per liter of recording solution) is added ,to prevent premature diazotization. Usually sumcient salt, NaCl, is used to of sodium ions equal to 1.0 gram molecular weights per liter, although good recordings have ben obtained in some cases with as low as 0.1 and as high as 3.0 gram molecular weights of sodium per liter. Other strong neutral electrolytes such as NaBr, KBr, KCl, LiCl, Bach, CaCh, MgCh, K2804, Na'iSO4, MgSO4, etc., may be substituted for sodium chloride.

It is obvious that various appropriate chemicals may be added to deepen the color or to improve the background permanency. The substitution of barium (and sometimes calcium) chloride for part or all of the sodium chloride makes the colors more blue in shade and faster'to washing,

usually lowers the solubility of the dye chemicals and not infrequently causes the formation of sludges which are of course objectionable. Complex cyanides of iron, chromium, or other metals sometimes improve dye to washing and deepen The addition of tartrates, formates, sulphites, hydrosulphites, thiosulphites, and/or other reducing agents results in a retardation of the background darkening, and in an extension of the useful working life of the solution by preventing slow chemical changes during storage, but is sometimes objectionable inasmuch as such reducing agents tend to decrease the sharpness of the detail of the recordings, to weaken the color of the dyes formed, and to require more electric current to produce the color.

Through the choice of primary amines and coupling compounds used a great variety of colors may be obtained, although orange, red and purple shades predominate. In general, the orange dyes give recordings whose backgrounds are more permanent without washing than the reds, purples or blues. Furthermore, it has been found that alpha-naphthalene compounds generally give darker colors, but with less permanent backgrounds, than the corresponding beta-compounds. f

It has also been found by experimentation that various dye chemicals are more responsive to the action of the electric current than others and in preparing the solutions such chemicals as are readily responsive to the action of the electric current should be used in order that the facsimile receiver may be operated at its maximum electrical and mechanical limits of speed. with the least responsive chemicals, reducing agents cannot be used for background preservation of facsimile recordings, due to the loss in color strength and sharpness of detail.

In the facsimile recording apparatus, stainless ture of diazonium compounds by passing the curmake the total concentration v oxidized by this steel, tungsten, molybdenum, platinum and platinum-iridium have been used as the contact electrodes. It has been found that where stainless steel electrodes are used, the purple, blue and some of the red dyes have a rusty appearance. It has also been found that theme of copper, nickel and certain other metals for the positive electrodes of the facsimile recorder is impractical, because they apparently inhibit From the above it may be seen, therefore, that an electric current may be'used in the manufacor less brilliant rent through alkaline solutions containing primary aromatic amines and sodium nitrite.

, Dye formation by electrolytic oxidation (III) is accomplished by the nascent oxygen available at the positive electrode whenever electric current flows through an electrolyte. When present in the electrolyte, chemicals capable of being oxidized to' form dyes frequently may be nascent oxygen, forming dyes only in the region immediately adjacent the positive electrode. Sometimes the acidity at this electrode also plays an important part in the formation of certain oxidation dyes. In addition, it is possible to produce either or both physical mixtures or chemical combinations of azo and oxidation dyes, if primary amines, nitrites and coupling compounds are also present in the electrolyte. Either or both the amino group which is diazotized electrolytically and the hydroxy or other group which directs coupling may or may not be attached to the molecules of one or more of the chemicals that are being oxidized. The oxidation may involve the Exaurnr: 5

Triphenylmethane d yes (oa'idation of a leuco compound) Ingredients Amount used (I) 4,4-tetramethyldiamino-4"-hydroxytriphenyl- 6.92 grams. (II) wfri -d ancaci 3.00 lwlvydrochloric acid normal) iocc ate! to a total vo ume of one liter.

The ingredients'are brought into solution with slight warming. The recording paper is immersed in the solution and then fed to the recording apparatus where it is subjected to electric current as described under azo dyes. With a steel positive electrode, bluish-green recordings on a very pale green background are obtained at the positive electrode. Copper, tungsten, molybdenum, or platinum electrodes give no recordings. On standing, both the recorded areas and Exnmmd Qutnonimine dues (union of two dye intermediates by oxidation) Formula Amount used Nnr-O-mcnomm Ingredients (1) Paraminod imethylanilinehydrochloride.

3.46 grams.

(II) Metaphenylenediamine-dihydrochloride.

3.62 grams.

NHLHCI (In Common salt NBC] (IV) Water to a total volume of one liter.

58.47 grams.

-The ingredients are dissolved in water, giving a pale yellow solution. Witha copper-containing positive electrode deep greenish-blue recordings on a white background are obtained, the color appearing on both sides of the sheet. With a steel positive electrode the color is weaker, and in a few minutes fades out to a still weaker shade. No recordings have been obtained with platinum, platinum-iridium, or tungsten electrodes. On standing for several days, the copper-produced recorded areas darken to blueblack, and the background also darkens. darkening is greatly reduced, but not eliminated, by washing the recordings with water within a few hours of their formation. The reaction is general in scope, as ingredient (I) may be'replaced by other paradiamines or by para-amino phenols, and ingredient (II) maybe replaced by other aromatic compounds having an unsubstituted ring position para to an amino or hydroxy group. Among the chemicals that have given this type of facsimile recording are:

Ingredient I Ingredient II m-Phenylenediamine Alpha naphthylamine Alpha naphthol Gamma acid. Chicago acid 8-hydroxylquinoline GENERAL DISCUSSION In any of the above mentioned examples it will be noticed that the electrodes per se do not play any part in the formation of the dye other than m as a means for subjecting the solution to an electric current, or as in the case of some oxidation dyes, where they. may act as catalysts. The metal or material of which the electrodes are made does not combine with the solutions of chemicals and does not enter into the compositicn of the electrolytically produced dyes. The electrodes may, in some instances, prevent the formation of the dye as stated above and by selecting a metal which will prevent dye formation for one of the electrodes the dye may be permitted to form on one side of the paper and prevented from forming on the other, even when the current is reversed. Such a choice of elecwhere alternatingcurrent is applied to the electrodes, or wherethe unrecorded side of a facsimile recording is to be used for a subsequent recording.

By the use oi any of the above mentioned solutions and compounds, it is possible to produce dyes and pigments by subjecting solutions or mixtures of chemicals to an electric current. Such dyes or pigments may then be collected in a paste, powder or liquid form and subsequently used for coloring paints, inks, etc., or for dyeing various materials. Also, materials such as clothing, piece goods, yarn, etc., may be dyed by im- 1 mersing such material in a container which has been filled with the solutions and subsequently subjecting the entire mixture to the flow of an electric current in order that the dyes may be fixed in the materials so immersed. This method produces a uniform coloring of the material, particularly when some agitation is present during the time that the electrical current is applied to the solution.

If it is desired thatnot all of the material be subjected to the electrical current in order that varying intensities of colors may be produced, or that designs or other patterns be printed on the material, it is obvious from the above that only portions of the material, all of which has been treated with the proper chemicals, need be subjected to the electric current and such selectivity of activation may be accomplished by controlling the distribution of current to various portions of the material either by controlling the current per' se or by applying a non-conducting material such as varnish, lacquer, paraflin, etc., to the material where it is desired that no current shall pass and no color shall be present. Furthermore, the material may be passed between a pair of rollers which are to act as electrodes of an' electric circuit and wherein one or both of the rollers is re cessed or engraved or otherwise altered in-contour or provided with non-electrically conductive areas in order that only portions of the material passing between the rollers will be subjected to the passage of current.

It is to be understood that, although the present invention is concerned primarily with the reproduction of printed matter, pictures, etc., by

trodes frequently is of particular advantage 7s a facsimilie system, the invention may well be applied to other fields, and in combination with other methods of dye formation.

Furthermore, it is to be understood that the invention, when applied to a facsimile receiver, may be used in such a manner as to produce a continuous process wherein the paper to be printed is fed from a roll and passed through the solution in order to sensitize the same. The paper so sensitized may then be directly transferred or fed to the facsimile receiver at which point the electric current causes the solution contained in the paper, to be changed into dyes in accordance with the values of the electric current. If desired, after passing through the facsimile receiver, the paper may or may not be automatically or otherwise exposed to light and/or directed to a fixing bath and subsequently washed in order to reduce the tendency for the background to discolor. After the paper has been washed it may then be passed automatically or otherwise to a dryer at which point the facsimile reproduction is completed and ready for perusal and storage.

The term facsimile as used herein is intended to involve not only the ceiver of a pre-existing subject, but also the rereproduction on the reception of subject matter in the process of crea-' tion or formation.

It is also to be understood that sheets of paper or material may be impregnated with one or another of the various solutions and the paper permitted to be subsequently dried. When the paper is dry it is relatively non-conducting and is not in a proper condition to be operated upon by the passage of electric current. The paper may then be humidified or dampened by any appropriate means, such as by steam or water vapor, for instance, in order to increase the conductivity thereof and the paper may then be placed in the facsimile receiving machine for use. By so preparing separate sheets of paper or separate rolls of paper it is possible to use the sensitized paper by merely subjecting the same to a certain degree of moisture in order that the current may pass therethrough and accordingly cause a dye to appear on the paper. I

It is also to be understood that paper, cloth, or other materials on which dyes are to be produced electrolytically may be subjected in whole or in part to any number of successive chemical treatments, and electric current applied to all cording on amaterial disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses which comprises, subjecting said material to the current between the electrodes while the material is suitably wet with an aqueous electrolytic solution containing hydrogen ions which provide anactive acid medium upon electrolytic action at the anode, at least one primary aromatic amine, and a source of nitric ions for diazotiz'ation, whereby primary amine is diazotized at the anode side of said material in accordance with the varying electric impulses, and providing at least one compound which couples with said diazotized amine to yield an azo dye.

2. The method of producing a facsimile recording in accordance with claim 1, wherein a coupling compound is provided which couples under alkaline conditions.

3. The method of producing a facsimile re cording in accordance with claim 1, wherein a coupling compound is provided which couples under acid conditions.

4. The method of producing a facsimile recording on a material disposed between elec-.

. trodes for transmitting electric current varying is diazotized in' the acid medium created by the electrolytic action at the anode in accordance with the varying electric impulses,and providing at least one compound which couples with said diazotized amine to yield an azo dye.

5. The method of producing a facsimile recording in accordance with claim 4, wherein a coupling compound is provided which couples under alkaline conditions.

6. The method of producing a cording in accordance with claim 4,- wherein a facsimile recoupling compound is provided which couples under acid conditions.

7. The method of producing a facsimile recording on a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses nitrite, whereby primary amine is diazotized inthe acid medium created by the electrolytic action at the anode in accordance with the varying electric impulses, and providing at least one compound which couples with said diazotized amine to yield an azo dye.

8. The method of producing a facsimile recording in accordance with claim '7, wherein a coupling compound is provided which couples under alkaline conditions.

9. The method of producing a facsimile recording in accordance with claim 7, wherein a coupling compound is provided which couples under acid conditions.

10. In a method of producing a facsimile recording-on a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses, the step which comprises, subjecting said material to the current between the electrodes .while the material is suitably wet with an aqueous electrolytic solution containing hydrogen ions which provide an active acid medium upon electrolytic action at the anode, at least one primary aromatic amine, and a source of nitrite ions for diazotization, whereby primary amine is diazotized at the anode side of said material in accordance with the varying electric impulses.

11. In a method of producing a facsimile recording on a material disposed between electrodes for' transmitting electric current varying inaccordance with applied electric impulses, the step which comprises, subjecting said material to the current between the electrodes while the material is suitably wet with an aqueous alkaline solution containing an electrolyte, at elast one primary aromatic amine, and a metallic nitrite soluble in alkaline solution, whereby primary amine is diazotized in the acid medium created by the electrolytic action at the anode in accordance with the varying electric impulses.

12. In a method of producing a facsimile recording on a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses, the

' the acid medium created by the electrolytic action at the anode in accordance with the varying electric impulses.

13. The method in accordance with claim 1 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine.

14. The method in accordance with claim 1 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine and couples under alkaline conditions. 7

15. Themethod in accordance with claim 1 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine and couples under acid conditions.

16. The method in accordance with claim 4 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine.

17. The method in accordance with claim 4 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine and couples under alkaline conditions.

18. The method in accordance with claim 4 wherein at least one coupling compound proi vided is identical chemically with at least one primary aromatic amine and couples underoacid conditions.

19. The method in accordance with claim 7 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine.

20. The method inaccordance with claim 7 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine and couples under alkalinetconditions.

21. The method in accordance with claim 7 wherein at least one coupling compound provided is identical chemically with at least one primary aromatic amine and couples under acid conditions.

22. The method of producing a facsimile recordingon a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses which comprises the steps of providing an alkaline solution containing at least one each of primary aromatic amines, metallic nitrites, and coupling compounds that couple under acid conditions, wetting the recording material with the solution, passing the treated material between recording electrodes, and subjecting the treated material to cording on a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses which comprises the steps of providing an alkaline solution containing at least one. each of primary aromatic amines, metallic, nitrites, and coupling compounds that couple under alkaline conditions, wetting the recording material with the solution, passing the treated material between recording electrodes, and subjecting the treated material to an electric current, fluctuating in accordance with the varying electric impulses, as it passes between the recording lectrodes, whereby anodic acidity causes the formation of one or more diazonium salts and subsequent ion migration between the anode and cathode sides of the material restores its original alkalinity and causes coupling to ensue, forming one or more azo dyes on predetermined portions of the material.

24. The method of producing a facsimile recording on a material disposed between electrodes for transmitting electric current varying in accordance with applied electric impulses which comprises the steps of providing an alkaline solution containing at least one each of primary aromatic amines, metallic nitrites and coupling compounds, wetting the recording material with the solution, passing the treated material between recording electrodes and subjecting the treated material to an electric current at the electrodes in accordance with the varying electric impulses whereby primary amine is diazotized at the anode side of said material'to form a basis for one or more azo dyes.

MYER SOLOMON. 

